For motor vehicles, speed control systems are known which allow the speed of the vehicle to be controlled to a desired speed selected by the driver. Moreover, it is possible to measure the distance from a vehicle ahead using a distance sensor, for example, using as a radar or lidar sensor. Then, the speed control is modified in such a manner that a predetermined, e.g., speed-dependent distance from the vehicle ahead that is selected as the target object is maintained. Such systems, which are also referred to as adaptive speed control systems or ACC (adaptive cruise control) systems, allow automatic longitudinal vehicle guidance under suitable conditions by intervention in the drive and brake systems. If the intention is to also implement automatic lateral guidance of the vehicle by intervention in the steering, for example, automatic lane keeping, additional data about the traffic infrastructure is required, e.g., data about the course and width of the lane.
In order to make such infrastructure data available in the vehicle, camera-aided systems have been proposed which allow the course of the roadway or lane boundaries to be detected by electronic image processing. To this end, sufficiently clear markings on the roadway or at the edge of the roadway are needed. The operational reliability of such systems could be improved by affixing additional markings in the form of reflectors to the roadway, to the guardrails, etc, in addition to the road markings that already exist today.
In www.path.berkeley.edu/PATH/Research/magnets (September 2001) and in R. Kasper/A. Kaiser: “Automatisches koordiniertes Fahren im Rechnerexperiment und Laborversuch” (“Automatic Coordinated Driving in the Computer Experiment and Laboratory Testing”), 3rd Mechatronics Workshop, University of Applied Sciences of Brandenburg, methods have been proposed which work with magnetic markers that are detected by a magnetic sensor mounted on the vehicle. The magnetic markers are, for example, embedded in the roadway pavement at the center of the lane at intervals of about one meter. Using different polarities of the makers, it is also possible, within certain limits, to wirelessly transmit digital information to the vehicle, for example, to indicate curves. However, installation of the magnetic markers in the roadway requires very great installation effort, and the information content conveyed by the markers can be changed later only with very great effort.
The object of the present invention is to provide a method for automatic vehicle guidance that can be implemented with little installation effort and adapted to changed conditions in a flexible manner.